Antibodies lipid conjugation

However, there are problems associated with the use of antibody—liposome conjugates for drug delivery in vivo. Particularly, since lipid vesicles are huge compared to... 

Fig. (10). Agar diffusion of different proteins and a lipid conjugated with lactose against anti-lactose antibodies (well L) and against anti-BSA antibodies (Well BS) wells 1-6 contained Lac-poly, Lac-BSA, Lac-sphingosine, Lac-ORA, Lac-HGG and BSA Chemical modification of the antigen by periodate oxidation or borohydride reduction can effect an agar diffusion against anti-gum arabic antibodies (Se), GA=gum arabic Bl=blank.

Reliable lipid and protein analysis of the prepared antibody-liposome conjugate is essential for proper characterization and subsequent interpretation of results obtained in the application of the conjugates. In addition, we strongly advise that the liposome conjugate size be determined with a particle sizer, if one is available, since liposome size plays such an important role in the pharmacokinetics of the system in vivo. 

Fig. 4. Aggregation reactions associated with different classes of antibody-liposome conjugates. (A) Antibody-liposome conjugates may react further with other liposomes to form aggregates. (B) The presence of PEG-lipids prevents these crosslinking reactions through steric hindrance. (C) Individual proteins may penetrate the PEG cloud to react with the liposome surface. (D) Antibodies tethered on the distal end of PEG may react with the distal ends of PEG molecules on a second liposome, resulting in crosslinking.

It should be noted that in our experience the liposome conjugation efficiency varies for different MAbs therefore, it is necessary to perform preliminary experiments to determine optimal initial antibody/lipid ratios. Other factors affecting conjugation efficiency include maleimide concentration, degree of thiolation, presence of PEG-lipids, and initial reagent concentration. 

Nanoprobes (www.nanobrobes.com) supplies 1 nm gold particles conjugated to a wide variety of compounds including antibodies, fluorochromes and lipids. Conjugates are available that may be applied not only to electron microscopy, but also light microscopy, and fluorescence microscopy. 

Arnon R, Teitelbaum D (1974) Lipid-specific antibodies elicited with synthetic lipid conjugates. Chem Phys Lipids 13 352-366... 

Other homogeneous immunoassays Several further homogenous assay formats have been developed that capitalize on the ability of antigen-antibody complexes to form detectable clusters or networks. Examples include the latex particle agglutination assay and the latex particle agglutination inhibition assay, in which the analyte or the antibody is conjugated to latex beads, and the analyte is quantified by virtue of its ability to promote or disrupt agglutination. Another example is the liposome immunoassay, in which analyte molecules are coupled to lipids,... 

Sato C, Kitajima K, Inoue S, Seki T, Troy FA II, Inoue Y (1995) Characterization of the antigenic specificity of four different anti-(a2,8-linked polysialic acid) antibodies using lipid-conjugated oligo/polysialic acids. J Biol Chem 270 8923-18928... 

The chemical adducts formed by reaction of aldehydes with lysine residues form highly immunogenic epitopes, and antibodies have been prepared specific for malondialdehyde- and 4-hydroxynonenal-conjugated LDL (Gonen et al., 1987 Yla-Herttuala et al., 1989 Jurgens et al., 1990). These antibodies cross-react with material in atherosclerotic lesions but not normal tissue, thus supporting the central role of lipid peroxidation in the patho nesis of atherosclerosis (Yla-Herttuala et al., 1989, 1991). 

Liposome conjugates may be used in various immunoassay procedures. The lipid vesicle can provide a multivalent surface to accommodate numerous antigen-antibody interactions and thus increase the sensitivity of an assay. At the same time, it can function as a vessel to carry encapsulated detection components needed for the assay system. This type of enzyme-linked immunosorbent assay (ELISA) is called a liposome immunosorbent assay or LISA. One method of using liposomes in an immunoassay is to modify the surface so that it can interact to form biotin-avidin or biotin-streptavidin complexes. The avidin-biotin interaction can be used to increase detectability or sensitivity in immunoassay tests (Chapter 23) (Savage et al., 1992). 

Lundberg, B. B., Griffiths, G., and Hansen, H. J. (1999), Conjugation of an anti-B-cell lymphoma monoclonal antibody, LL2, to longcirculating drug-carrier lipid emulsions,... 

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